They RARELY blitzed prior to the 4th quarter. Early in the game you never saw more than 3-4 guys rushing the passer.
A blitz is defined as sending more then 4 rushers or sending any defensive back in to rush. So 3 down lineman plus 1 linebacker is not a blitz.
I have yet to see a QB with a higher Passer rating for his career against constant pressure, than when a defense drops 8 or 9 into pass protection. Yes against some QB's who can't play on the nfl level (russel...) this works just as well, if not better, since he cannot hit his own receivers, maybe he will hit our Dbs. but for the most part, a great QB will tear apart 8 dropped into coverage when he has all day to throw. When he is on his back, he can't do that....
According to former Saints QB Bobby Hebert (who does sports talk now and the pre and post game shows on radio) who played during the last era that the 3-4 held sway in the NFL, you are correct. The terminology of his day referred to 3 down linemen + 1 linebacker rushing the QB as a "dog", while 3 down linemen + 2 or more linebackers or 1 or more defensive backs was a "blitz". Don't know what today's "football terminology police" are codifying as correct, but anyway...